Single-photon sources and detectors are key enabling technologies for photonics in quantum information science and
technology (QIST). QIST applications place high-level demands on the performance of sources and detectors; it is
therefore essential that their properties can be characterized accurately. Superconducting nanowire single-photon
detectors (SNSPDs) have spectral sensitivity from visible to beyond 2 μm in wavelength, picosecond timing resolution
(Jitter <100 ps FWHM) and the capacity to operate ungated with low dark counts (<1 kHz). This facilitates data
acquisition at high rates with an excellent signal-to-noise ratio.
We report on the construction and characterization of a two-channel SNSPD system. The detectors are mounted in a
closed-cycle refrigerator, which eliminates reliance on liquid cryogens. Our specification was to deliver a system with
1% efficiency in both channels at a wavelength of 1310 nm with 1 kHz dark count rate. A full width at half maximum
timing jitter of less than 90 ps is achieved in both channels. The system will be used to detect individual photons
generated by quantum-optical sources at telecom wavelengths. Examples include single-photon sources based on
quantum dots (emitting at 1310 nm). The SNSPD system's spectral sensitivity and timing resolution make it suited to
characterization of such sources, and to wider QIST applications.
Light emission at 1.54 μm from an Er-doped amorphous silicon nitride layer coupled to photonic crystal resonators
and plamonic arrays is studied. We observe the cavity resonances at cryogenic and room temperatures and under
varying optical pump powers. The results demonstrate that small mode volume, high quality factor resonators
enhance Er absorption rates dramatically at the cavity resonance. Photonic crystal cavity resonances exhibit
linewidth narrowing with pump power at cryogenic temperatures, signifying absorption bleaching and partial
inversion of the Er ions. In addition, we fabricate periodic metal-insulator-metal plasmonic structures with a
simple bottom-up fabrication technique. We observe a factor of 10 increase of Er emission coupled to plasmonic
structures.
The recent advances in superconducting nanowire single-photon detector (SNSPD or SSPD) technology has enabled
long distance quantum key distribution (QKD) over an optical fiber. We point out that the performance of SNSPDs play
a crucial role in achieving a secure transmission distance of 100 km or longer. We analyze such an impact from a
simplified model and use it to interpret results from our differential-phase-shift (DPS) QKD experiment. This allows us
to discuss the optimization of the detection time window and the clock frequency given the detector characteristics such
as dark count rate, detection efficiency, and timing jitter.
We report on the photoresponse mapping of nanowire superconducting single-photon detectors using a focal spot
significantly smaller than the device area (10 μm x 10 μm). Using a solid immersion lens we achieve a spot size of 320
nm full-width half maximum onto the device at 470 nm wavelength. We compare the response maps of two devices: the
higher detection efficiency device gives a uniform response whereas the lower detection efficiency device is limited by a
single defect or constriction. A second optical setup is used to simultaneously image and measure the photoresponse of
the lower detection efficiency device, allowing the constriction location to be pinpointed.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.